On 1/5/2011 9:38 PM, Richard Schneider wrote:
>
> Hi Jim,
>
> I probably should have mentioned that once the car is started there is 
> no noise. So I've ruled out ignition EMF.
>
> The noise spikes are only present during initial startup and upon 
> shutdown. They only last a fraction of a second. That's why I think it 
> comes from the alternator field building on stratup and collapsing on 
> shutdown.
>
> Richard
>
>
>
> On Wed, Jan 5, 2011 at 3:32 PM, Jim Santee  > wrote:
>
>     Go to a professional two way radio shop – NOT RADIO SHACK – and
>     purchase an ignition noise suppression kit. Some professional
>     marine dealers have these as well. What they usually consist of
>     are high quality by-pass capacitors placed on the alternator and
>     ignition module. One point: Check with your automobile dealer
>     service department to ensure you will not void your warranty or
>     damage your ignition system. Thirty years ago this would not have
>     been necessary as there were no computers or sensors in the
>     electrical systems of cars.
>
>     Police cars have radio interference problems so these kits are
>     fairly common. Finding a kit for your car should be easy.
>
>     Jim Santee
>
>

  If I were going to guess, I'd say that the problem was from the 
hundreds of amps drawn from the battery when the starter engages. I've 
seen copper cables jump a half inch while starting.
A combination of magnetic and electrostatic shielding might help, but 
I'd apply it at the seismometer, not at the car.
If you want more detail, let me know.

Daryl





  
    
  
  
    On 1/5/2011 9:38 PM, Richard Schneider wrote:
    

        
Hi Jim,
        
I probably should have mentioned that once the car is started
          there is no noise. So I've ruled out ignition EMF.
        
The noise spikes are only present during initial startup and
          upon shutdown. They only last a fraction of a second. That's
          why I think it comes from the alternator field building on
          stratup and collapsing on shutdown.
        
Richard
      

      

      
On Wed, Jan 5, 2011 at 3:32 PM, Jim
        Santee <jsantee@............>
        wrote:

        

          

            

              
Go to a professional two way radio
                shop – NOT RADIO SHACK – and purchase an ignition noise
                suppression kit. Some professional marine dealers have
                these as well. What they usually consist of are high
                quality by-pass capacitors placed on the alternator and
                ignition module. One point: Check with your automobile
                dealer service department to ensure you will not void
                your warranty or damage your ignition system. Thirty
                years ago this would not have been necessary as there
                were no computers or sensors in the electrical systems
                of cars. 
              
 
              
Police cars have radio interference
                problems so these kits are fairly common. Finding a kit
                for your car should be easy.  
              
 
              
                
Jim Santee
              
          
        
      
      

    
    

     If I were going to guess, I'd say that the problem was from the
    hundreds of amps drawn from the battery when the starter engages.
    I've seen copper cables jump a half inch while starting.

    A combination of magnetic and electrostatic shielding might help,
    but I'd apply it at the seismometer, not at the car.

    If you want more detail, let me know.

    

    Daryl